Heat exchanger



March 12, 1935. H, VQRKAUF 1,994,009

HEAT EXCHANGER Filed May 17, 1932 6 Sheets-Sheet l l INVENTOR HE/Nfi/CH VO/FKA UF BY 15 ATTORNEY L March 12, 1935. H. VORKAUF HEAT EXCHANGER Filed May 17, 1932 6 Sheets-Sheet 2 l N v E NTOR HHA/P/CH Momma/ Y H15 ATTORNEY hsrmm Mafch 12, 1935,

6 sheets-wsheet 3 Filed May 17, 1932 I I h l *5 l I i I ---J l I J INVENTOR Him/m VOA KAUF BY H l 5 ATTORNEY March 12, 1935.

H. VORKAUF HEAT EXCHANGER 0 Filed May 17,, 1932 6 Sheets-Sheet 4 INVENTOR Hfl/V/P/CH VORA'A UF BY Hls ATTORNEY/UM 5 mm.

March 12, 1935. H. VORKAUF 1,994,009

' HEAT EXCHANGER Filed May 17, 1932 6 Sheets-Sheet 5 BY ATTORN EY H ls March 12, 1935. H: VORKAUF 1,994,009

HEAT EXCHANGER Filed May 17, 1952 6 Sheets-Sheet 6 BY-W ' ATTORNEY Patented Mar. 1 2, 1935 UNITED STATES HEAT EXCHANGEE Heinrich vorkauf, Berlin, Germany, ass'ignor, by mesne assignments, to the firm Heme & Workauf, Berlin, Germany Application May 1'7, 1932, Serial No. 611,849

In Ger-ma 24 Claims.

This invention relates to the generation and utilization of steam and especially to the generation of steam and its, utilization to produce mechanical power. lhe invention more particularly relates to the generation of steam and the development of power'irom it in a prime mover of the rotary type. v

- Heretofore steam has commonly been generated in steam boilers arranged as separate, units from which the steam may be withdrawn through pipes for use at a point remote from the boiler. When used for the production of mechanical power the steam has been carried through pipes to so-called prime movers which utilized the energy of the steam by causing its pressure to act upon a movable element of the prime mover. Commonly the steam is expanded in the prime mover from the boiler pressure to a lower pressure, usually less than atmosphere and is exhausted from theprime mover to a condenser. In such constructions not only has it been necessary to provide a large number of joints in' the pipe leads and in the connections between the boiler and the prime mover,

of operation, especially in the use of high pres-' sures. These faults contribute to the difliculties of operation and the limitation of output.

The present invention provides a novel process of generation of vapor, particularly in connection with the generation of mechanical power by a rotary prime mover and provides novel means for carrying out said process of vapor generation.

Moreover, the invention makes use of the rotary from which the vapor or the steam is to be generated is subjected to theaction of centrifugal force. A mass of the liquid to be evaporated is caused to revolve about an axis and thus, as is well known, the mass will be subjected to centrifugal force of an amount which depends upon the speed of revolution; When said. speed of revolution is sufficiently high, for example, is a speed such as may be provided by a rotary prime mover, the centrifugal force acting upon the mass of liquid is sufficient to produce in the liquid, when confined, a substantial pressure. This pressure, for example in the case of water, may be as great as that at which steam usually is generated for power or other purposes. In fact, it is possible to produce by this method a pressure considerably greater than that at which vapor is usually generated from water or from other liquids, such as mercury, which have been used for the genera- May 20, 1931 vention the centrifugal force or action is utilized to cause flow of the liquid or of the water through a path of liquid flow. By suitably arranging the direction of said path of liquid flow in relation to the revolution of the mass of the liquid, that is, with respect to the axis of revolution, the liquid may be caused to flow in said path outwardly from saidaxis under the action of the centrifugal forces due to the revolution of the mass of the liquid about the ams. Moreover, while flow- 10 ing in said path under the action of centrifugal force the pressure of the liquid may be raised, gradually from a relatively low pressure adjacent the axis to a considerably higher pressure at a point in the path remote from the axis.

Such a path of flow of the liquid or of the water may be provided by arranging a tube in an approximately radially relationto a shaft. If by suitable means the liquid such as water is delivered to the end of said tube adjacent the shaft and if the shaft is rotated ata suitable speed, the water will flow outwardly from said shaft through said tube under the action of centrifugal force and the pressure of the water confined in the tube will be gradually increased in a direction 20 along the tube outwardly} from the shaft. Moreover, by suitable connections to a. reservoir or other water storage the rotation or revolution of .the tube itself may be utilized to draw water from said reservoir and to cause the flow of the water under said centrifugal action through the tube to a point therein remote from the shaft.-

If now the liquid, while subjected to centrifugal force in said path and at the pressure created,

therein due to centrifugal force, is subjected to 30.

vapor generating heat, vapor may be generated from the liquid at substantially the pressure to which the liquid or water has been raised by the centrifugal action. Such vapor may be generated from the liquid delivered to a path of flow ior heat exchange, which path is a continuation of the path of liquid flow in which the liquid was subjected to centrifugal action.

Moreover, although the invention is not limited to flow of the vapor in any particular direction,

advantageously in many cases the path of how for such heat exchange and for vapor generation may be such that the flow of the vapor or of the mixture of vapor with the liquid from which it is being generated is opposed by the centrifugal action which produces the flow of the liquid as described. Such a path of flow for vapor generation may be inwardly toward theaxis of revolution from the point in the path of liquid flow to which, under centrifugal action, the liquid has been delivered.

11 a tube is used for flow of liquid or water therethrough in heat exchanging relation to a source of heat, such a tube also may be placed approximately radially with respect to a shaft (5!! such as that above mentioned in relation to which the water flow tube was radially arranged. By such an arrangement of the tubes, as mentioned above, the water may be delivered to the shaft end of the water tube and steam and any water mixed therewith may be discharged from the shaft end of the steam generating tube. By simply connecting the tubes at their ends remote from the shaft the water for steam generation may be passed from the water tube to the steam generat ing tube. It will now be clear that substantially by this arrangement there is provided a U-tube having its ends adjacent the shaft and having the bend thereof remote from the shaft. In such a tube when rotated upon said shaft at a suitable speed the water and the steam will be subjected to the centrifugal force tending to impel the mass of the water or of the steam or of the steam and water mixture outwardly toward the bend.

It will be apparent that if such a path of water flow, that is. such a path as is provided by a U-shaped tube, were filled in both legs of the U with water or with steam or any other fluid there would beno unbalanced force available to produce flow of the fluid therethrough from one end of the path to the other, that is, first outwardly from the axis and then inwardly toward the axis. However, if one portion of the path is subjected to heat sufliciently to generate from the liquid vapor which thereby will occupy, relative to the liquid, a considerable space and which therefore will have a density considerably less than the liquid from which it was evaporated, an unbalance will be produced in the centrifugal forces acting respectively upon the vapor or upon the mixture of the vapor with the liquid from which it was evaporated in said heated path and in the other path upon the liquid without admixture of vapor. This unbalance, therefore, will be available to produce flow of the liquid outwardly from the axis, as described above, with the corresponding increase in the pressure of the liquid, and this increase in pressure will provide the force against which the vapor by its usual expansive action will flow inwardly toward the other end of the path adjacent the axis. Moreover, such an expansive, flow producing action will take place while the vapor is generated at a pressure substantially equal to that which the water has been raised by the centrifugal action.

Thus it is possible by the present invention to feed a liquid substantially along an axis of revolution to a path of flow so related to the axis that the liquid will flow first outwardly from the axis under the action of centrifugal force and then inwardly toward the axis together with the vapor generated therefrom. To produce this flow it is necessary, however; that the substantial generation of vapor in the outward flow of the liquid be prevented or limited to such adegree that it does not substantially interfere with the centrifugal action upon the liquid and with the increase in hydraulic pressure thereof. It is also necessary that for the most part the steam be generated in the portion of the path beyond said portion through which the water flows outwardly 4 from the axis. This vapor generating portion of the path may return toward the axis as stated above. Thereby the steam and any water mixed therewith is opposed by the centrifugal force acting thereon, but the flow in said portion of the path is produced by the hydraulic pressure created in the water in the portion of the path in which it flows outwardly from the axis.

By mounting or otherwise suitably arranging tati ng elements of Figure 8.

the vapor generating element, as described above, upon a shaft which is an extension of a shaft of a rotary prime mover, the requisite rotation or revolution of the element may be provided. Moreover, in such case, as will be clearly understood from more detailed description to follow in connection with the drawings, the vapor generated in the element may be utilized directly in the prime mover without first withdrawing the vapor from the element or from the vapor generator to a point outside the generator and then redelivering it to the prime mover. The vapor may be delivered along the shaft of the prime mover and then through a suitable conduit outwardly to the nozzle or other expansion device for development of the power by expansion in the usual manner.

Constructions according to the invention are suitable for use with two or more fluids, for example, in the binary cycle using water and mercury, and the steam discharged from the prime mover may be used to heat the second fluid, As the rotating steam generator is especially adaptable for high pressures, the secondary steam generator may serve as a condenser for the fluid evaporated in the rotary steam generator and expanded in the prime mover connected thereto. The pressures at which the primary and secondary vapors are generated are determined by the operating condiitons and the purpose for which the steam or vapor or the mechanical power is to be used.

In; another phase of the invention provision is made for impelling the gases to flow over the rotating steam generating elements by so forming the elements or providing them with blades or fins that they act as a fan or blower to propel the gases through the space in which the elements are revolving. The gases may thus be caused to flow, for example, from a furnace to a stack without the use of auxiliary blowers or suction fans. The invention thus provides an efficient construction for the transfer of heat from gases moving. at high velocity.

Other features and advantages of the invention will be understood from the more detailed description to follow in connection with the drawings in which:

Figure 1 shows a vapor generating element of the type of the invention mounted upon a rotating shaft;

Figure 6 shows a plant comprising a rotating steam generator with a prime mover connected thereto in combination witha common type of boiler; v

Figure 7 shows a rotating vapor or steam gen erator connected in a fluid flow circuit;

Figure 8 shows another modification of the vapor generator of the invention;

Figure 9 is a cross section on line 9-9 of Figure 8i and Figure 10 shows a cross section of one of the tubes of Figure 8.

Figure 11 shows an enlarged view of'the ro- Figure 12 is a section upon line l212 of Figure 11.

The simplest form of operation of such a rotating steam generator is a two-legged tube, as illustrated in Figures 1 and 2. When liquid is poured into a U tube, as long as this tube is not heated the liquid in both legs remains of equal height and a state of rest is brought about. If, however, the one leg l of this tube is heated, which can be brought about by protecting leg 2 from the effect of hot gases by means of a separating wall, either warm water or a mixture of vapor and water is produced in the heated leg 1. The specific weight of this liquid is less than the specific weight of the unheated liquid in leg 2.

, The result of this is that a driving force is produced, which corresponds to thedifference of weight of the column of fluid in both legs 1 and 2. The driving force is not particularly high when the two-legged tubes are at rest. However, this force will be substantially increased if the tube is revolved or rotated, whereby the two-legged tube will be exposed to a considerably greater acceleration than the acceleration of gravity.

These conditions are illustrated in Figures 1 and 2. According to Figure 1, the liquid to be evaporated is delivered from the receptacle placed above stuffing-box ,5 into the rotating hollow shaft which is rotated or revolved by suitable driving means 60, from which hollow shaft it fiows into leg 2 of U-tube and from here into leg 1,

whereby U-tube becomes completely filled with the liquid if the receptacle 4 is at a sufiicient height.

If leg 1 is heated by gases which do not reach leg 2 because of separating wall 3, then vapor or steam is generated in leg 1 which is displaced and leaves the U-tube by way of the left end of the hollow shaft 6 and stuffing box '7.

Figure 2 shows a two-legged tube, whose legs are not parallel, but at right angles to each other. Here also the liquid is delivered from the receptacle 4 above the stuffing box into the 1101- low part of shaft 6, which shaft is rotated, and

the liquid fiows fromhere into leg 2 of the twolegged tube. By means of gases, which heat leg 8 but are kept separate from leg 2 by separating wall 3, steam is generated in leg 8, which steam is displacedand flows out of leg 8 into collector 9 and leaves the apparatus by way of conduit 10.

In practical operation one two-legged tube, as shown in Figures 1 and 2, could naturally not deliver sufiicient steam. These drawings only show that in principle it is possible to operate the process of invention by rotating two-legged tubes or tube systems of various forms if care is taken to have steam generated in only one leg of the tube or tube system and to have the zenith of the two-legged tube or tube system lying on the outer circumference of the rotating member.

As illustrated in Figures 3 and 4, a two-legged tube system having tubes 1 and 2 is arranged on thehollow shaft 6, which tube system also is brought into rotation by means of the rotation of the hollow shaft 6. The water or other liquid to be evaporated is delivered from the highly positioned receptacle 4 over the stuffing box 5 into the right end of the hollow shaft 6 and from here flows into leg 2 ofthe rotating tube system. The liquid is led through distributing tubes or headers 11 into tubes 1, then fiows from here by way of the tube system 13 into the left side of the hollow shaft 6, in order to leave the-apparatus by way of the stufling box '7. As long as no heat is applied to the tubes, according to the law of commun'icating tubes these tube's will become filled with water. If, however, the tubes 1 are heated,

for example by conveying heating gases through' the rotating system in the direction of the arrow, the steam produced will be displaced from tubes 1 and will flow over by way of the left end of the hollow shaft 6 to a place of use. Through suitablemeans of construction, if necessary by providing separating walls, as shown at 3 inv Figure 1, between the tubes 2 on the one hand and tubes 1 on the other hand or by arranging tubes 2 in such a zone of temperature of the heating medium as to prevent steam formation at the actual pressure in tubes 2, care must be taken not to allow' of any substantial steam formation in tubes If the generated steam encounters any resistance, for example through a throttle or a power machine, then the pressure of this steam increases, and the steam now displaces the water in the heated tubes 1. In the case when all the water from tubes 1 is to be displaced the necessary steam tension can be estimated. In such case it must be equal to the difference of the pressure through the centrifugal action of the water in tubes 2 and the pressure through the'centrifugal action of the steam in tubes 1.

If the specific weight of the water is set equal to l and the specific weight of the steam equal to 0.1, the diameter of the rotary member equal to 3.0 ft. and the number of rotations occurring every minute equal to 4000, then the pressure due to the centrifugal action of the water is estimated at 2530 lbs. per square inch. The pressure due to centrifugal action of the steam amounts to 253 lbs. per square inch. Apart from the friction in the tubes, the steam, under the assumed conditions, could be generated with a pressure of 2270 pounds per square inch.

A substantial advantage of the process of invention consists in this, that the high pressure of the water necessary for feeding is generated in the boiler itself. This results in the water delivery conduit being under only a very slight pressure, and all connections, such as stufling boxes and other fittings, need not be constructed for high pressure as is generally the case in the existing high-pressure steam generators.

The. withdrawal of the steam takes place through connecting header 12 and a superheater 13, in which the steam is dried and superheated.

Figure 5 shows the connection of a rotating steam generator with a prime mover. The steam generator and the prime mover are coupled together in such a manner that a connected assembly results, in which steam is generated, which is expanded in the'prime mover in order to generate energy. The expanded steam is discharged into a condenser or, depending on the pressure of the exhaust, steam is led into a low pressure turbine or used for heat purposes. The present construction of the .steam power plant also affords the possibility of avoiding all connecting pipes together with their fittings between the steam gen-- erator and the prime mover. In this way the space taken up by the entire plant becomes less than that of the existing plants, which results in by way of the tube system 2 into the distributing headers 11 and from here into the tube system 1 and is generated in the steam. Through the difference between the centrifugal action of the water and that of the steam or steam water mixture in tubes 2 and 1 a substantial increasing of pressure takes place. The steam generated in tube system 1 flows through the shaft 6 into the superheater 13, and in it is heated to the desired temperature. From here itflows into the steam turbine 15.

It is advantageous to allow the steam to exe pand from the middle of the turbine either in axial or radial direction, as then all stuffing boxes or other connecting positions under high pressure can be abolished.

The regulation of the speed of revolution may take place by means of altering the quantity of heat supplied, i. e. the quantity of fuel burned. This could take place, according to Figure 5 by allowing a speed regulator 50 or a device responsive to the speed of the machine to control burner 16, or a thermostat subjected to the heat of the steam could also control the fuel delivered. For

,example, a speed regulator 50 may be connected as by electrical means to operate fuel valve 51 or the thermostat 1'? may be connected to control this valve.

The regulation of the amount of water which is fed to the steam generator preferably may be accomplished in relation to the temperature of the generated steam. When this steam is delivered to a prime mover such as a turbine, as illustrated in Figure 5, the temperature utilized may be that of the steam after expansion in the first stage, or the temperature may be taken at some other point in the expansion, in order to avoid placing the thermostatic element in the shaft of the steam generator. As may be seen from Figure 5 the thermostatic element may be placed in the casing of the turbine and subjected'to the temperature of the steam flowing from the first revolving element of the turbine. This thermostatic element 1'7 is connected to control the regulating valve 14. For practical purposesthis may serve to control the feed to the steam generator as effectively as if. the thermostatic element were placed in the shaft of the apparatus at the outlet of the steam generator.

This thermostat is operated in such a manner that when the temperature of the steam is too high in this turbine chamber, the 'regulating valve 14 is opened to enable more fluid to pass into the steam generator, while if the temperature of the steam is too low in said turbine chamber the regulating valve is throttled so that less fluid passes into the steam generator,- thus causing the temperature of the superheated steam to rise.

As the steam power plant according to the invention must be started up by means of an auxiliary energy supply, a special starter 61 which may include a motor of suitable'type is provided, such as an electric motor or steam turbine supplied from a separate source of power or of steam, which sets the steam generator into rotation by starting up the whole apparatus. The pressure of the generated steam is thus considerably increased so that the turbine is driven by means of this steam and the starter can then be cut out by any suitable disconnecting means or gearing which may be interposed between the starter 61 and the shaft of the rotating steam plant.

It is also possible to use the auxiliary steam which is led through conduit 18 into the first turbine chamber. In this case it is necessary to shaft 6 and superheater 13 into turbine 15 and drives this turbine. The auxiliary steam may then be shut off.

It is hardly necessary to call attention to the fact that this steam power plant of the invention is neither limited to stationary installations nor to the evaporation of water alone. It can be used just as well for any kind of motor vehicles. It is very well suited for the evaporation of mercury, since in mercury steam plants owing to the high price of mercury and the danger to health, which problems come into consideration because of leaky joints with the attendant loss of, themercury vapor, it is a question of a steam generator with the smallest possible liquid content and the greatest possible reductionincioints, all of which in the steam generator plant according to the invention is provided for in the highest degree.

Figure 6 shows an example of how, in a further embodiment of the invention, the above described primary steam power plant can be coupled with an ordinary stationary boiler plant. In this embodiment a chain grate stoker is shown. A sectional boiler, an existing fire tube or internally fired boiler or any other boiler with any desired heating method would also be suitable.

As illustrated in the drawings, the gases are delivered from the common furnace chamber 20 by way of the conduit 21 into the rotating steam generator 22, and leave it by way of conduit 23. They then flow through the tube bundle of the bent tube boiler and thus give off their heat for the preliminary heating of the liquid contained in the bent tube boiler.

The steam produced in the rotating steam generator 22 then reaches the prime mover 15 which is arranged on the same shaft with the steam enerator 22 and is expanded to a greater or less degree in this prime mover.

The expanded steam now leaves the prime mover 15 by way of conduit 24 and flows through the serpentine tube bundle 25 provided in theupper drum of the bent tube boiler, where it is condensed. The condensate flbws through the conduit 26 to the rotating steam generator 22, where it evaporates in order again to start on its path through the circuit as described.

The pressure at which the steam is exhausted from the prime mover 15 and delivered to the coil 25 determines the pressure at which the steam is generated in the bent tube boiler 27. In general it is advantageous to exhaust the steam from the prime mover at a higher pressure than the pressure of the secondary steam in the boiler 27 as there is obtained in this case particularly favorable heat transfer conditions and very simple constructive possibilities. However, these conditions are determined also by the kind of liquids that are to be vaporized. These conditions may vary, according to whether a single stage, two stage or multistage system is under consideration. Moreover, consideration must also be given to the difference between the pressure of the primary steam generated in the steam generator 22 on the one hand and the secondary steam generated in the boiler 27 on the other hand, since the pressure of the primary steam in the coil 25 in the upper drum of the bent tube boiler 27 must ary steam takes place.

' this receptacle.

cessitating the construction of a very expensive be so high that a "heat drop between the condensing primary steam and the generated second- This heat drop must be sufficient for the generation of the secondary steam.

The combination of the primary and secondary plants is especially advantageous in the operation with mercury vapor. The temperature of the mercury vapor, even over a considerable range of expansion, is still so high that-a steam plant must be added. In such a case mercury vapor would be produced and expanded in the power plant 22, 15 and would then, upon condensing and cooling, produce secondary steam in the boiler plant 27.

The generated secondary steam can then be utilized in a prime mover 28 which is either coupled with the prime mover 15 or is separately arranged. The whole apparatus can serve for the operation of a generator 29, or its energy can be utilized in some other manner. If no secondary steam is generated but only hot water is produced the plant can also be used under such operating conditions as are desired.

It is, however, not always necessary to operate the steam generator in such a way that evaporation of the liquid is complete and a drying as well as superheating of the vapor results. The pressure produced by centrifugal action can also be used to produce a circulation of the liquid through the tube system. Figure '7 illustrates the embodiment of this idea in a form which. will serve as an example. As is to be seen in this drawing, the fluid to be vaporized travels'towards the rotating steam generator from the elevated receptacle 4 through the conduit 30. A steam water mixture is then produced in the steam generator, which leaves the steam generator by way of stufiing box 7 and is ,led through conduit 31 to the elevated receptacle 4. A separation of the liquid and the steam takes place in The separated steam leaves the elevated receptacle 4 through conduit 32 to be conducted to a place of use while the unevaporated liquid is again delivered to the steam generator through conduit 30, in order again to start on the circuit as described.

' The steam generator in this embodiment has no superheating coil 13 such as is illustrated in Figure 3. I

Figure 5 also is different from Figure 3 in that the steam generated in tubes 1 is not conducted away through headers 12 arranged on shaft 6, but is withdrawn directly through hollow shaft 6.

. Another embodiment of the invention is illustrated in Figures 3 and 9. The liquid to be vaporized in this case is delivered from the elevated receptacle not shown into the tube system 2 and then flows through the distributing headers 11 into the vaporizing tubes 1. These tubes are arranged staggered and may be of such form that due to the rotation of the steam generator a fan action is produced which effects the suction of the, gases from duct 33 and its conveyance through the steam generator and its discharge through the outlet 35. It is, of course, possible to arrange the steam generator tubes 1 or the water inlet tubes 2 in other-ways in order to produce this fan action-' This arrangement has the advantagethat the gases, for the purpose of increasing the heat transfer and therefore the specific steam generation, 1. e. the steam generation per unit of surface, may be led through the steam generator with greater speed without nesuction fan installation.

Such a method of producing combined heat exchange and fan action has the advantage that the losses resulting from eddies in the gas are regained as heat. Moreover, as the fan action is produced bythe heat transfer elements themselves, a suction fan at the outlet of the generator with its attendant disadvantage of air'inflltration and the resultant reduction of efllciency is avoided. In the present invention as the heat exchanger or steam generator itself draws the gases from the furnace and delivers them through the rotating heating surface a more uniform pressure is maintained throughout the gas flow and air infiltration is avoided. Such a heat exchanger has the advantage that it may operate without extreme draft loss through the heating surface without providing either a high force draft pressure or great suction in order to produce the necessary pressure 'drop for delivering the gases through the heating surface. In the steam generator of the present invention the pressure difference in the gases before and after the heating surface is only small and the resistance within the heating surface itself is overcome by the fan action of the rotating heating surface.

The embodiment of the invention, as shown in Figures 8 and 9, is also advantageous in providing flow of the flue gases in an axial direction through the heating surface elements arranged upon the shaft. The delivery of the heating gases may be accomplished byintroducing them near the shaft at one end and discharging them at the circumference of the steam generator at the other end. By arranging the steam generating elements in a staggered screw-like arrangement with.

surfaces through duct 33 at the left side of the rotating steam generator. At the right side of the steam generator the fiue gases are forced out through the waste gas passage 35.

The tubes 1 and 2 may be provided with fins 70 asshown in Figure 10. These tubes are also illustrated in an enlarged view as shown in Figures 11 and 12. As will be seen from Figures 11 and 12, the planes of fins '10 are inclined to the axis of the shaft 6 and these fins-produce a movement of the gases in the direction'of the arrows as shown in Figure 10 or axially along the shaft 6 when the proper direction of rotation is given to the shaft 6. By greater or less inclination of the fins to a plane at right angles to the axis of rotation, the rate of delivery of the flue gases may be modified. As will be seen from Figure 12, the tubes are arranged in staggered relation along the shaft and circumferentially around the shaft. It will be clear from the above description and from the drawings that the transfer of heat from the gases to the tubes land 2 is effected while at the same time these tubes produce the necessary flow of the gases into contact with said tubes. If provision is made for the introduction of the gases into the casing 34 at a point near the shaft asshown in Figure 11 the centrifugal fan action of the tubes as at 80 acting upon the gases may be utilized to produce flow from a point at the circumference of the casing, in which case the fins may be omitted;

The rotating steam generator arrangedfor fanaction as described is suitable not only for direct fired steam generating plant but also may be used for waste heat installations, as such steam generators require a draft to accomplish the movement of the gases over the heating surfaces. The invention is also applicable to other installations where heat is transferred to a fluid flowing through heating elements, which elements are rotated and in which the rotation may be used for causing movement of the fluid to be heated or of the gases for heating or both.

It is to be seen from the above explanations that the process of generating steam according to the invention can be used in all cases where steam is to be produced from water or from other fluids, for

7 example mercury, for power or heating purposes.

In consequence of the easy and space-saving construction of the steam generator of the invention it can be used not only for stationary and marine boiler construction, but also for any kind of vehicles, for example automobiles, locomotives or airplanes.

. What is claimed is: r

1. A heat exchanger comprising a heat exchange element of the type providing a deflned path in which a fluid is heated while flowing therein, means for delivering the fluid to be heated to said element for flow therein, means for withdrawing the heated fluid from said element, means for revolving said element as a whole about an axis of revolution, said element being so arranged with respect to said axis of revolution that the fluid is delivered to said element adjacent said axis and so that the centrifugal force of said revolution acts upon said fluid in at least a part of said element so as to tend to produce flow of the fluid outwardly from said axis in said part, and means for so limiting the heating of said part of said element as to prevent the expansion of said fluid while in said part to a state so expanded as to interfere substantially with the flow producing action of the centrifugal force in'said part while heating a portion of said element succeeding said Part in the direction of flow of the fluid to a state sufficiently expanded so that said centrifugal force actingupon said unexpanded fluid may cause said fluid to flowthrough said element and to discharge said expanded fluid therefrom.

2. A vapor generator comprising a vapor generating element of the type in which the vapor is generated from liquid flowing therein, means for delivering liquid to said element for flow therein, means for withdrawing vapor from said element, means for revolving said element as a whole about an axis of revolution, said element providing a continuous path of flow from one end thereof to the other and being arranged so that the liquid inlet end thereof is adjacent said axis and so that the liquid under the action of the centrifugal force of said revolution flows through a portion of the element outwardly from said axis, and means for so limiting the heating of said portion of the element as to prevent the generation in said portion of the element of vapor from said liquid in amount sufilcient substantially to interfere with the 'fiowproducing action of the centrifugal force upon said liquid while heating a succeeding portion of said element sufiiciently to generate therein vapor from the liquid delivered thereto, said vapor and any liquid in excess thereof being caused to flow through said succeeding portion under the force created b the centrifugal action upon said liquid in said portion in which the liquid flows outwardly from the axis.

3. A steam generator comprising a steam genpath in which the steam is generated from water flowing therein, means for delivering water to said element for'fiow therein, means for discharging steam from said element, and means for revolving said element as a whole about an axis, the arrangement of said element with respect to said axis being such that the water is delivered to said element adjacent said axis and under the action of the centrifugal force of the revolution is caused to flow therein outwardly from said axis while the steam is withdrawn from the other .end of the element, and means for so heating said element as to generate steam therein and to discharge steam therefrom while substantially preventing the generation of steam in said portion of the element in which the water flows outwardly from said axis.

4. A vapor generator comprising a vapor generating element of the type providing a defined path in which the vapor is generated from liquid flowing therein, means for delivering liquid to one end of said element for flow therein, means for revolving said element about an axis of revolution whereby the liquid within said element is subjected to the action of centrifugal force, said element being so arrangedwith respect to said axis of revolution that the liquid is delivered to said element adjacent said axis and is caused by the centrifugal force to flow through said element outwardly from the axis with a concomitant increase of its pressure, means for generating vapor in said element from the liquid at said increased pressure while flowing in said element, and means for preventing during said outward pressure-increasing flow heating of the liquid to such a degree as to cause the formation of vapor in an amount sufiicient substantially to interfere with said increase in pressure of the liquid.

5. A steam generator comprising a steam generating element of the type providing a defined path in which the steam is generated from water flowing therein, means for delivering water to one end of said element, means for revolving said element about an axis not coincident with the path of flow provided by the element, said element being so arranged with respect to said axis that the water inlet end thereof is adjacent the axis and so that the water delivered thereto is caused by centrifugal force to flow outwardly from said axis in at least a portion of the element adjacent said water inlet end thereof, said element having a portion succeeding said first portion and subjected to heat sufficient to generate steam from water fiowing therein, and means.

for so limiting the heating of said first portion as to'prevent the generation of steam therein in amounts sufficient to interfere with producing by said centrifugal force in the water flowing outwardly therein a pressure capable of causing fiow of water together with the steam generated therefrom in said succeeding portion and to discharge the steam therefrom.

6. A steam generator comprising a tube arranged substantially radially with respect to an axis of rotation, means for delivering water to said tube at the end thereof adiacent said axis, means for rotating said tube about said axis to cause the water under the action of centrifugal force to flow in said tube outwardly from said axis, means connected to the end of said tube remote from the axis and providing succeeding the outward flow in said tube a path of flow in.

heat exchanging relation to a source of steam generating heat for the water discharged from said end of the tube remote from said axis, and means for so limiting the generation of steam in said radial tube as not to interfere with the action of said flow producing centrifugal force upon the 'water to cause said water to be delivered into and to flow in said path in heat exchanging relation to said source of steam generating heat.

7. A steam generator comprising a tube arranged substantiallyradially with respect to an axis of rotation, a second tube arranged substantially radially with respect to said axis, a connection between the ends of the tubes remote' from the axis, means for applying steam generating heat to said second tube, means for delivering water to said first mentioned tube at the end thereof adjacent said axis, means for removing the generated steam from the end of said other tubeadjacent said axis, and means for rotating the tubes about said axis at a speed such that the water in the first mentioned tube and the steam and any water in the second mentioned tube are subjected to the action of centrifugal force, and the difference in the ,pressure produced by the differences of the centrifugal forces resulting from the difference between the weight of the water in the first tube and the weight of the steam and any water in the second tube causes flow of the water outwardly from said axis in said first tube and flow of the steam and any water. inwardly toward said axis in said second tube.

8. A steam generator comprising a plurality of tubes arranged substantially radially with respect to an axis of rotation, means for applying steam generating heat to some of said tubes while limiting the amount of heat applied to others of I said tubes to avoid steam generation, means for delivering water to the ends of said tubes subjected to a limited amount of heat at the ends thereof adjacent said axis, means for withdrawing the generated steam from the ends of said other tubesat the ends thereof adjacent said axis,

' means connecting the ends remotefrom the axis of said tubes subjected to limited heat with the ends remote from the axis of said tubes subjected to steam generating heat, and means for rotating all said tubes about said axis at a speed sufiicient to produce a pressure in the ,water' in said tubes subjected to limited heatat least equal to the pressure of the generated steam, whereby the water delivered to the ends of the tubes adeachproviding water inlet end jacent to the axis is caused to flow outwardly through said tubes subjected to limited heat and to be delivered to said tubes subjected to steam generating heat for generation of the steam therein substantially at said pressure.

9. A steam generator comprising a plurality of steam generatingelementsof the type in which the steam is generated from water flowing therein, a shaft upon which said elements are mounted, means for delivering water to said elements at one end ofeach thereof, means for revolving said elements in a group as a whole upon said shaft acting as an axis of revolution, said elements a defined path oi flow from the thereof to the other end thereof and being arranged so that the water inlet ends thereof are adjacent said shaft and with a portion of each element adjacentits water inlet end extending outwardly from said shaft, whereby the water withinsaid portion of each element is subjected to the action of centrifugal force acting generally in a direction along the path of flow provided by said portion of said element, means lovsteam generator according to claim 9 in I which the shaft is hollow in at least a portion thereof,- and said elements have at least one end thereof connected to said hollow space to provide for flow of fluid through said space and through said tube in a direction determined by said flow impelling action of the centrifugal force.

11. Steam generator comprising a hollow shaft, at least two tubes each connected at one end thereof to said shaft and extending outwardly from said shaft as an axis, means for rotating said shaft and said tubes about said axis, means for delivering water to a portion of the hollow space of said shaft connected to oneof said tubes, the other of said tubes being subjected to steam gen= erating heat and being connected into a portion of the hollow space of said shaft separated from the portion of said hollow space into which the water is delivered, means connecting the outer ends of said two tubes to form therewith a defined path of flow from one hollow space of, the shaft to' the other, said tube to which the water is delivered being subjected to heat insufficient to generate steam in such amount with respect to the water contained in said tube as to prevent the development in said water by the action of centrifugal force of a force at the outer ends of said tube capable of impelling the water to flow through said connection and inwardly in said other tube tegether with-the steam generated from the water and to discharge the generated steam into said. other portion of the hollow shaft.

12. Steam generator according to claim 3 in which a plurality of the steam generating elements are arranged about an axis and in which are provided means for distributing the water to the individual elements so as to cause it to flow through the generator in a general direction parallel to said axis, and means for causing heating gases to flow over the heating elements in a direction generally parallel to the axis. 1

13. Steam generator according to claim 3 in which a plurality of the, steam generatingelements are arranged about an axis and in which are provided means for distributing the water to the individual elements so as to cause it to flow through the generator in a general direction parallel to said axis, and means for causing heating gases to flow over the heating elements in a direction counter to the flow of water.

14. Steam generator'comprising a shaft, a pin-- other and to said shaft as to provide gas-propelling surfaces when said shaft is rotated upon its axis, means for'rotating said shaft. to produce flow of gases over said steam generating elements, and means for collecting the steam discharged from said steam generating elements.

- 15. Steam generator according to claim 14 in which the water to be evaporated is delivered along said shaft to the inner ends of said steam generating elements and is subjected in said elements to the action of centrifugal force due to the rotation of said elements upon said shaft to cause the water to flow through said steam generating elements.

16. Steam generator according to claim 14 in which the steam generating elements are in the form of tubes arranged radially about said shaft in staggered spiral relation thereto.

17. Steam generator according to claim 14 in which the steam generating elements are in the form of tubes arranged radially about said shaft,

in staggered spiral relation thereto, said tubes being provided with fins in such angular relation to a plane at the right angles to the axis of the shaft as to provide a gas-propelling surface.

18. Process of heating a fluid which comprises delivering the fluid to be heated into a positively defined pathof fluid flow, subjecting the mass of said fluid while in said path to the action of centrifugal force tending to produce flow of the fluid along a portion of said path, limiting the heating of said fluid in said portion of said path to prevent expansion thereof while in said portion of 'the path to a state so expanded as to interferev substantially with the flow producing action of the centrifugal force of the fluid in said portion, and heating the fluid in a succeeding portion of said path to a state so expanded that the centrifugal force of said unexpanded fluid may cause flow through said succeeding portion of said path of the 'fluid delivered from said first portion and may cause discharge of the expanded fluid from said path.

19. The process of generating vapor from a liquid which comprises subjecting said liquid to the action of centrifugal force to increase the pressure thereof while so limiting the heating of the liquid as to prevent the generation-from said liquid of vapor in amount suilicient to interfere with saidincrease in pressure and utilizing said pressure of the liquid to cause flowv thereof in a defined path in heat exchanging relation to a source of heat for generating vapor from said liquid while flowing in said path.

20. Process of generating vapor from a liquid which comprises delivering the liquid intoa path of liquid flow, subjecting said liquid in said path to the action of centrifugal force to cause said liquid to move in said path and to raise the pressure of the liquid, applying to said liquid at the increased pressure and while subjected to said centrifugal force heat suflicient to generate vapor therefrom at said pressure but limiting the heating of the liquid to prevent substantial generation of vapor from said liquid prior to its acquiring while flowing in said path said pressure under the action of the centrifugal force, and utilizing said pressure to cause flow of the water in said path in heat exchanging relation to the source of heat.

21. Process of generating vapor from a liquid in a vapor generating element of thetype providing a defined path in which the vapor is generated from liquid flowing therein which comprises deliverlng to said element the liquid to be evaporated, revolving said element about an,

axis of revolution so as to subject the liquid in said element to the action of centrifugal force,

through the element outwardly from said axis and to raise the pressure of said liquid, so limiting during said outward movement of the liquid in said element the heating thereof as to prevent the generation of vapor in amount suflicient to interfere with raising the pressure of the liquid, utilizing said pressure to cause the liquid to flow through a portion of the element succeeding said portion in which the flow is outward from said axis, generating vapor from said liquid flowing in said succeeding portion, and utilizing the flow impelling action of said pressure to cause the vapor to flow inwardly toward said axis against the centrifugal force acting on said vapor.

22. Process of generating vapor from a liquid which comprises causing the liquid to flow in a predetermined path under the action of centrifugal force acting directly upon the mass of liquid flowing in said path to increase the pressure thereof, preventing prior to its acquiring said increased pressure heating of the liquid sumciently to generate from said liquid vapor in amount capable of interfering with the increase of said pressure, passing said liquid while at said increased pressure and while subjected to centrifand being positioned with one end thereof adjacent said axis, so that said path of fluid flow extends inwardly toward said axis, means connecting said conduit and said element at a point remote from said axis to provide for fluid flow from one to the other, means for delivering the liquid to be vaporized to said end of the conduit 1 adjacent said axis, means for revolving s'aid conduit and said element about said axis, whereby the liquid in said conduit is subjected to centrifugal force tending to produce flow thereof outwardlyin said conduit, means for preventing in said conduit the generation of vapor in such amount with respect to the liquid contained thereinas to interfere with the development in said liquid by the action of the centrifugal force of a force at the outer end of said conduit capable of impelling the liquid through said connection and inwardly in said element together with the vapor generated therein and to discharge the vapor from the inner end of said element.

24. Process of heating a fluid which comprises delivering a liquid to be heated into a defined path of fluid flow, subjecting the mass of said liquid to the action of centrifugal force while in said path, limiting the heating of the'liquid in a portion of said path to prevent substantial formation of vapor while subjecting the liquid in a portion of said path succeeding said first, 

